Tone control signal circuit having tone pulses followed by continuous tone

ABSTRACT

A control signal generator circuit for an annunciator such as an electric tone in the form of a buzzer or bell consisting of three principle circuits: a timer circuit; a multivibrator; and an amplifier circuit. These circuits are connected across a single power supply. The multivibrator provides the function of producing a series of pulses to the amplifier circuit for causing the annunciator to operate on an intermittent basis. The timer circuit provides the function of converting the operation of the annunciator from producing an intermittent audio signal to a continuous audio signal after a predetermined period of time.

[ Oct. 10,1972

United States Patent Kawaki et al.

W mm CS ME m NT 8 m u m um ww aw L C rm A Nm mm U m? n TO T 0 N Ell mmTH m 3,284,796 11/1966 Borsattino..............340l384 E 3,504,3643/1970 Abel..... ...340/384 E Primary Examiner-Harold T. Pitts BYCONTINUOUS TONE [72] inventors: Katsumi Kawaki; Mmshi Usui,

both of Kawasaki, Japan Assignec: Tokyo Tokei Selzo Kahlil, Ltd.,

Attorney-Carothers and Carothers Kawasaki-shi Kanagawa-ken, Japan Dec.3, 1970 Appl. No.: 94,825

ABSTRACT [22] Filed:

A control signal generator circuit for an annunciator 1 such as anelectric tone in the form of a buzzer or hell consisting of threeprinciple circuits: a timer circuit; a

multivibrator; and an amplifier circuit. These circuits [30] ForeignApplic'fion mm! are connected across a single power supply. The mul-June 10, 1970 Japan 45 514 tivibrator provides the function of producinga series of pulses to the amplifier circuit for causing the annunciatorto operate on an intermittent basis. The timer circuit provides thefunction of converting the operation of the annunciator from producingan inter mittent audio signal to a continuous audio signal after apredetermined period of time.

RmR m m Wma 36m wm 0 m 3 m I L 0 d S M Ul F HUN um 4 Claims, 2 DrawingFigures V V Tmse AsrA r/c M04 77 VIBRA r012 AMPLIFIER (1260 I T TONECONTROL SIGNAL CIRCUIT HAVING TONE PULSES FOLLOWED BY CONTINUOUS TONEBACKGROUND OF THE INVENTION The present invention relates to a controlsignal circuit which may be conveniently employed as a ringing tonegenerator in an alarm clock.

The prior art tone generator generates a ringing tone continuously fromthe beginning of its ringing operation to the end of its ringing cycle.Recently, two-step type tone generators have been used which are adaptedto generate, for a predetermined period of time from the time of initialringing, a low frequency ringing tone, a low level ringing tone or anintermittent ringing tone and thereafter to generate a continuousringing tone. I-Ieretofore, most of these two-step type ringing tonegenerators have been operated through the provision of mechanical means.Consequently, they have the disadvantages of being complex in structure,difficult in manufacture, and quite apt to become faulty after verylittle use.

In view of the fact that recently electric timepieces which make use ofelectric energy as a driving source for the timepieces have been widelyused, it is preferable from the standpoint of compactness andsimplification in manufacture of timepieces, as well as durability andlasting use, that the ringing tone for an alarm also be generatedelectrically.

SUMMARY OF INVENTION The principle object of the present invention isthe provision of an electric tone generator driving circuit, which isadapted to operate an electric tone generator (for instance, a buzzer oran electric bell) intermittently for a predetermined initial period oftime and then continuously for a subsequent period of time to provide atwo-step type of electric tone signal generator. This also provides analarm ringing tone generator for an electric alarm clock having anelectric two-step system.

Another provision of the present invention is a twostep type controlsignal circuit characterized by an electric power supply circuitincluding an electric power source and a power source switch, a timercircuit including a charging circuit comprising a transistor having itsbase connected with a capacitor in the charging circuit, an astaticmultivibrator, and an amplifier circuit for amplifying the output signalfrom the astatic multivibrator and applying it to an electric tonegenerator which forms the load in the amplifier circuit. The timercircuit, the astatic multivibrator and the amplifier circuit areconnected in parallel to the electric power supply circuit. A loadresistor provided in the timer circuit is also the biasing resistance ofthe astatic multivibrator.

According to the present invention, during the charging periods of thecharging circuit the oscillatory pulses of the astatic multivibrator areamplified by the amplifier circuit and then applied to the electric tonegenerator forming the load in the circuit. Consequently, the electrictone generator is operated intermittently to generate an intennittenttone. However, when the charging of the capacitor in the chargingcircuit has been carried out to a predetermined voltage level, thetransistor in the charging circuit is turned on so that a current flowsthrough the load resistor. Since this load resistor is in common withthe biasing resistor of the astatic multivibrator, the oscillatoryaction of the astatic multivibrator ceases; consequently, a currentflows directly through the load of the amplifier to generate acontinuous tone. Thus, tone signal generation is enabled to operate in atwo-step manner, first intermittently and then continuously. It is alsopossible to generate the intermittent tone for a desired time intervaland to regulate the period of generation of the intermittent tone byadjusting the time constants of the astatic multivibrator and thecharging circuit, respectively.

Other objects and advantages appear in the following description andclaims.

The accompanying drawings show, for the purpose of exemplificationwithout limiting the invention or the claims thereto, certain practicalembodiments illustrating the principles of this invention wherein:

FIG. 1 is a circuit diagram of the tone signal generator circuitcomprising this invention.

FIG. 2 is a graphic illustration of the current waveform flowing throughload 2 in the amplifier circuit of Fig. 1.

Referring now to the figures, in Fig. I, the block encircled by a dottedline 1 represents the timer circuit utilizing a charging circuit. Thedotted-line block 2 represents the astatic multivibrator, and thedotted-line block 3 represents the amplifier circuit containing anelectric tone generator Z such as a bell or a buzzer which forms theload for the circuit. The switch means S is connected in series with thepower supply E which is a d.c. source provided in any convenient mannerwell known in the prior art. The charging capacitor C l is connected inseries with the charging resistor R1 both of which are connected acrossthe power supply E by means of supply lines 4 and 5. An NPN or PNPtransistor TRl is used in the charging circuit and is operative when thecharging capacitor has reached a predetermined voltage level.

The astatic multivibrator 2 comprises the gating resistor R2 connectedon one side to line 4 and on the other side to the emitters of bothtransistors TR2 and TR3. The transistors TR2 and TR3 may be of the PNPor NPN type to perform the oscillating function. The resistors R3 and R4are the load resistors of the astatic multivibrator 2. The R-C circuitsrepresented as C2 and R6 connected to the base of transistor TR3, and C3and R7 connected to the base of transistor TR2 are the A-C time constantsettings for the multivibrator circuit.

In the amplifier circuit 3, TR4, which may be a PNP or NPN transistordevice, has its base connected to the collector of transistor TR3, whileits emitter is connected through the biasing resistor R5 to one side ofthe power supply B through line 4 as in the case of bias ing resistor R2and charging resistor R1. The collector of transistor TR4 is connectedto the load Z of the amplifier circuit 3 which is an electric tonegenerator such as a bell or buzzer in an alarm clock or other suchtimepiece.

The timer circuit 1 and the astatic multivibrator 2 are connected incommon by line 6 through the gating resistor R2, while the multivibratorcircuit 2 and the amplifier circuit 3 containing the electric tonegenerator Z are directly connected through line 7. Each of thesecircuits 1, 2 and 3 are connected in parallel to the power supply bymeans of supply lines 4 and 5.

Assuming now that the switch S within the internal mechanism of thetimepiece has been closed, power is supplied from the power source Ethrough lines 4 and 5 simultaneously to the charging circuit in thetimer circuit l the astatic multivibrator circuit 2, and the amplifiercircuit 3. The gating resistor R2 serves both as a load resistor for thecharging transistor TRl in the timer circuit 1 and as a series resistorin the emitter circuits of the transistors TR2 and TR3 in the astaticmultivibrator circuit 2, and is connected commonly to each of thesecircuits to achieve a gating effect.

The multivibrator 2 is connected to the power supply E through thegating resistor R2 so that a square waveform voltage is generated acrossthe resistor R4 depending upon the time constant determined by thecapacitors C2 and C3, and the resistors R6 and R7. This square waveformvoltage is amplified by transistor TR4 in the amplifier circuit 3, and,thus, an intermittent waveform of current flows through its output side,that is, through the tone generator Z. The period of this intermittentwaveform can be selectively determined by appropriately selecting thecapacitors C2 and C3 and the resistors R6 and R7 to choose the timeconstant.

With the switching on of switch means S, an electric charge is graduallystored in the capacitor C1 through the resistor R1, the potentialdifference between the base and the emitter of transistor TRl increasingin accordance with the time constant determined by the capacitor C1 andthe resistor R1. When this potential difference reaches a predeterminedvalue, the transistor TRl becomes conductive and current flows throughline 6 to the gating resistor R2 in the load circuit of transistor TRl.As a result, there is an abrupt voltage drop across the gating resistorR2. Since gating resistor R2 serves also as a series resistor for theastatic multivibrator circuit 2, a biasing voltage is applied to theemitters of transistors TR2 and TR3 of the astatic multivibrator 2, andtherefore, multivibrator 2 stops its oscillatory action.

Simultaneously with the ceasing of the oscillatory action of the astaticmultivibrator 2, the load resistor R4 of the oscillator circuit servesas a biasing resistor for transistor TR4 in the amplifier circuit 3, sothat the base potential applied at the transistor TR4 is lowered,resulting in a continuous current through the tone generator Z toprovide for its constant operation.

Referring now to Fig. 2, the period Tl, which is the intermittentsounding tone, is determined by the time constant of the capacitors C2and C3 and the resistors R6 and R7 in the astatic multivibrator 2. Theselectable period T2 of the intermittent sounding tone which ends at thestarting point of the continuous sounding tone is determined by the R-Ctime constant of the capacitor Cl and the resistor R1 in the timingcircuit 1. The period T3 is the time when the continuous sounding toneis being generated, that is, a constant current I across the load Z, andcontinues until the switch means S is opened.

From the foregoing, it can be seen that a two-step type alarm tonegenerator is provided by means of a simple electric circuit, simplifyingthe structure of an alarm clock or other such timepiece. Accordingly,this makes it possible to provide for an alarm clock with a two-stepelectric type alarm tone generator which is simple to manufacture andvirtually incapable of wearing out when comparing such alarm devices tothose of the mechanical type.

Although what has been described above has been directed to a controlsignal circuit as applied to an electric alarm clock, it is a matter ofcourse that the present invention need not be limited to such aparticular application, but instead it can be generally applied to anytype of annunciator.

We claim:

I. A control signal circuit for controlling the current flow through anannunciator to cause intermittent operation followed by continuousoperation of said annunciator comprising a timer circuit having acharging capacitor and resistor connected in series and a transistorhaving its base connected between said charging capacitor and resistor,a multivibrator having its input connected to said timer circuit, anamplifier circuit having said annunciator as a load, said timer circuit,said multivibrator and said amplifier circuit being connected inparallel and across a power supply, the output of said multivibratorcircuit being coupled to the input of said amplifier circuit so thatsaid annunciator may be intermittently activated by the repetitiveoutput frequency signal of said multivibrator, said timer circuitincluding a gating resistor as a load thereof which is connected to saidmultivibrator for biasing and to cease the operation of saidmultivibrator when said charging capacitor is charged to a predeterminedpotential value causing said annunciator to be continuously activated.

2. The control signal circuit of claim 1 characterized in that saidamplifier circuit includes a transistor having its base connected acrosssaid power supply through biasing resistors.

3. The control signal circuit of claim 1 characterized by switch meansconnected in series with said power supply to place said circuit inoperative condition.

4. A control signal circuit for operating a mechanical annunciator firstby providing an intermittent signal to said annunciator for itsoperation followed by a continuous operation comprising a timer circuit,a multivibrator, and an amplifier circuit all connected in parallel andacross a power supply,

I. said amplifier circuit comprising an annunciator connected in serieswith an amplifier transistor, the base of which is connected across saidpower supply through biasing resistors ll. said multivibrator comprisingtwo transistors with companion RC networks and accompanying loadresistors, the output of said multivibrator connected to the base ofsaid amplifier transistor between said biasing resistors ll]. said timercircuit comprising a charging capacitor and charging resistor connectedacross said power supply with a timer transistor connected across saidpower supply in series with a gating resistor, said timer transistor andgating resistor also connected to the emitters of said multivibratortransistors, the base of said timer transistor connected between saidcharging capacitor and said charging resistor and 6 IV. switch meansconnected in series with said power annunciator when said chargingcapacitor has supply to place said circuit in operative conditionreached a predetermined potential causing concausing duction of saidtimer transistor and a voltage a. said multivibrator to produce anintermittent P acfoss gatmg to signal on said annunciator to causeintermittent 5 cease the y action of Sam mumvlbl'a' operation of thelatter; and b thereafter causing continuous operation of said

1. A control signal circuit for controlling the current flow through anannunciator to cause intermittent operation followed by continuousoperation of said annunciator comprising a timer circuit having acharging capacitor and resIstor connected in series and a transistorhaving its base connected between said charging capacitor and resistor,a multivibrator having its input connected to said timer circuit, anamplifier circuit having said annunciator as a load, said timer circuit,said multivibrator and said amplifier circuit being connected inparallel and across a power supply, the output of said multivibratorcircuit being coupled to the input of said amplifier circuit so thatsaid annunciator may be intermittently activated by the repetitiveoutput frequency signal of said multivibrator, said timer circuitincluding a gating resistor as a load thereof which is connected to saidmultivibrator for biasing and to cease the operation of saidmultivibrator when said charging capacitor is charged to a predeterminedpotential value causing said annunciator to be continuously activated.2. The control signal circuit of claim 1 characterized in that saidamplifier circuit includes a transistor having its base connected acrosssaid power supply through biasing resistors.
 3. The control signalcircuit of claim 1 characterized by switch means connected in serieswith said power supply to place said circuit in operative condition. 4.A control signal circuit for operating a mechanical annunciator first byproviding an intermittent signal to said annunciator for its operationfollowed by a continuous operation comprising a timer circuit, amultivibrator, and an amplifier circuit all connected in parallel andacross a power supply, I. said amplifier circuit comprising anannunciator connected in series with an amplifier transistor, the baseof which is connected across said power supply through biasing resistorsII. said multivibrator comprising two transistors with companion RCnetworks and accompanying load resistors, the output of saidmultivibrator connected to the base of said amplifier transistor betweensaid biasing resistors III. said timer circuit comprising a chargingcapacitor and charging resistor connected across said power supply witha timer transistor connected across said power supply in series with agating resistor, said timer transistor and gating resistor alsoconnected to the emitters of said multivibrator transistors, the base ofsaid timer transistor connected between said charging capacitor and saidcharging resistor and IV. switch means connected in series with saidpower supply to place said circuit in operative condition causing a.said multivibrator to produce an intermittent signal on said annunciatorto cause intermittent operation of the latter; and b. thereafter causingcontinuous operation of said annunciator when said charging capacitorhas reached a predetermined potential causing conduction of said timertransistor and a voltage drop across said gating resistor sufficient tocease the oscillatory action of said multivibrator.